The present invention relates to implementation of a hybrid (metal-composite) ship hull concept and a material-transition structural component, including a hybrid joint, that is to connect material-dissimilar hybrid hull structures for producing hulls for ships, to a ship hull containing the same, as well as to a method of manufacturing of the material-transition structural component and the ship hull.
It is known to use for construction of ship hulls a combination of two classes of structural materials, metals, which are commonly quite strong but heavy and prone to corrosion, and fiber-reinforced polymer-matrix composites, which are generally light-weight and corrosion resistant. These hybrid hulls may embody either a primary metal hull with incorporated composite structural components, such as bulkheads, platforms and topside structures among others, or, opposite, a primary composite hull/structure outfitted with metal hardware, such as deck mooring bits, chocks and cleats among many others.
A series of recent patents and scientific-technical papers [1-5] enlighten the hybrid hull idea with regard to major hull structures of a primarily metal ship, bow and stern sections as well as midship side panels. These conceivable applications are associated with assorted potential functional, structural, and operational benefits.
Particularly, the anticipated benefits include weight saving, corrosion prevention, increased inclination stability, lowered life-cycle cost, augmented deadweight/displacement ratio, and improved propulsion characteristics, all of which are critical to boost a vessel's speed and/or non-refueled range. Along with those, composite/hybrid structures are preferred to improve signature control of a naval vessel.
It has been however recognized that benefits of the hybrid hull implementation is in large depending upon structural efficiency of composite-to-metal transition structure or a hybrid joint that is typically notably lower than that of neighboring mono-material structural components, either metal or composite. The lowered performance of a material transition structure is due to several traits inherent to a fiber-reinforced composite being interrupted within a material-transition (or a joint) structure that is well documented to date [6-9]:                Discontinued fiber reinforcements        Relatively low out-of-plane mechanical properties        Stress concentration attributable to both joint's intricate geometry and abrupt change of material stiffness within a joint        Complicated manufacturing procedure relevant to a two-/multi-material structural system        Underperformance of secondary (post-cured) bond, if any        Tightened requirements to metal contact surface preps.        
To compensate these adverse impacts, assorted measures are to be implemented. Typically, those comprise enlargement of adhesive bonding area and/or incorporation of mechanical fastening (such as bolting, screwing or riveting).
Nevertheless, even a hybrid joint that combines adhesive bonding with fastening that represents the current state-of-the-art in heavy-duty hybrid joining being used over a range of industry sectors while possesses the highest structural efficiency available to date is yet excessively heavy and labor intense due to massive hole-drilling and fastening (e.g., bolt-nuts coupling) operations.
Patents [5, 10] disclosure an advanced method of structurally efficient composite-to-metal joining that combines adhesive bonding with transverse pinning of the composite to the metal by tiny projections/features protruded from the metal surface by application of a power beam, e.g., an electron beam or a laser beam.
Such bonded-pinned hybrid joints demonstrate an opportunity to gain great structural efficiency superior to that of common joining options, both plain adhesive bond and bonded-fastened joint [9, 11, 12] while being commensurate in labor and cost with those of a plain adhesive bond. This advanced bonded-pinned joining technology is potentially applicable for a material-transition structure regarding any hybrid hull component that includes but not limited with bow and stern sections, midship side panels, bulkheads, platforms, deckhouse, and foundations for machinery and equipment as well as other heavily-loaded ship structures, such as rudders, impellers and waterjet inlet tunnels among others.
A number of peculiarities inherent to implementation of this novel class of joints are to be taken into consideration and relevant requirements critical for a bonded-pinned joint performance must be satisfied in order to attain the desired high level of structural performance of the joints. Specifically, those are to provide:                Tight contact between composite and metal elements        Complete incorporation of the projection pins of metal element into composite element        Sufficient resistance of the pins to in-plane loading        Proper penetration of polymer resin into fiber material of the composite element as well as into cavities being intruded within the metal element simultaneously with its protrusion.        
Most of design-manufacturing parameters, primary contributing to performance of said bonded-pinned joint, are interconnected and mutually influential. Due to that, variation of those parameters may cause a contradictory effect, either increasing or decreasing a joint's structural performance. In particular, principal dimensions of a protrusion pin, such as its base and height responsible for the pin's in-plane resistance, if excessive, impede provision of two other vital traits, proper penetration of the pins into composite and tight contact of adjacent composite and metal elements. Similarly, disproportionate toughness of the composite element interferes with its permissibility to the pins incorporation into the composite.
To abate those contradictions, a proper balance between joint's parameters needs be provided in order of attaining its high structural performance. Along with that, certain modification of conventional composite material processing providing simultaneous metal-composite consolidation is to be implemented.